?'s on puttin a cr or yz motor in trx 90

[06yfz450mxer]

Iv'e seen on the net where guys have put a cr engine in these chassis , Is there a kit ?? and can u use the stock pipe from the bike ?? whats all needed ??????????? please give me info thanks joejoeboxer72@yahoo.com

[bracey]

no they dont have a kit it will take some work i have a custom made pipe for a kx 85 motor in a trx 90 i will sell for 75.00 plus shipping thanks

[fcfab]

It is not the easiest thing to do but well worth it when done right. If you have choice I would go with the raptor 250, easier to find long travel set ups.
If you go with the Cr 85 the pipe well have to be cut and re shaped.
Carey
Fc Fabricating

[06yfz450mxer]

Would love to do that but the way d3 runs the quad mini class they have no in between class so its 90cc then right to the big boy toys , so the apex quads run away with it right now , My son like to shift so I want to keep it to what he likes ........

[st8jacket]

my brother just put a cr80 engine in a 250r frame to build my nephew a 90 mod..fairly straight forward,hardest part was the engine mounts,but they were simple..The head pipe was extended a lil bit so it sits down low and tucked up against the frame like it was built for it..

[st8jacket]

here it is the day before it was started for the first time

[06yfz450mxer]

LOOKS SWEET MAN , I HOPE THIS TURNS OUT WE HAVE SEEN A COUPLE WITH A CR MOTOR IN A 90 CHASSI SO TIME WILL TELL .

[tireman43]

I haven't built one or had a lot of experience, so correct me if I'm wrong...I thought a motor mount from the 400ex would work for the CR85 swap in these. I was thinking I read that some place and even saw pictures. Just my .02 cents.

Kevin

[woodsracer144]

i think if you do it you should do it with the 90 chassie... the 250r is the lighter of the bigh quads that i've seen with them in but like said before if you use a bigger quad frame i would use a raptor 250.. there set up like a yfz they are realyl close just a little smaller...

if your still gonna run the JR. i would use the 85 motor in a 90...


in D23 i have never watched a 90 race....ever only seen them as pit quads... they have a 300ex jr class where its the 200 2 stroke to a 300 4 stroke and thats all for little kids this is also in hairscrambles.

[blazen582]

This is a stock TRX 90 frame with PR2 built CR 85 engine in it.. It was not hard.. I used 400 ex motor mounts for the front and made rear mounts. The pipe I cut it 2 inched from the head and turned it then re welded.. I did not have to make it shorter or longer where I cut it just turned it.. I used KOQ's front and swinger.. Really nice stuff! Don't do the ebay front brackets.. Did that first and still have the bent ones to show! When I decided to do this alot of people on here helped me along with Tom from KOQs.. I have pictures of the build if they will help you.. The hardest was to find a rear sproket to fit the 400 axle but use the same chain as the CR 85 engine, untill... I called Hetrick and they had everything in stock to make it work!! We drag race this bike here in VA.. Unbeatin so far.. "knock on wood!" That is why the tires are on there. Plus since the pics I have put Elkas all the way around it..

Anyways Anything I can do to help let me know..

David

[blazen582]

Another

[blazen582]

OOHHH By the way.. Not talking bad about Apex!! We ran one last year.. Could not keep it together.. I think I went to big with the motor (112 I think it was) even had it built by a shop.. and it kept running hot. BUT let me know if you need to see some video's of some apexs in the next lane!... to a true 85cc Cr motor.. Ok it does have alot of other work done to the motor but it is still a 85cc!

[TEXWS6]

Originally posted by blazen582
Another

looks good, let's see some other pics!!!

[06yfz450mxer]

Thanks for all the info , we r looking to tear into this quad over the winter and put the cr85 engine in. What I have seen and heard thats the way to go. Thanks to all.....

[yamaharacer47]

I got a yz80 engine and we r going to put into a 300ex chassi any helpful thoughts out there ??

[fcfab]

The yz 80 works well in the 300ex. the only problem I forsee is the kick starter needs to be moded
Carey

[woodsracer144]

Originally posted by blazen582
This is a stock TRX 90 frame with PR2 built CR 85 engine in it.. It was not hard.. I used 400 ex motor mounts for the front and made rear mounts. The pipe I cut it 2 inched from the head and turned it then re welded.. I did not have to make it shorter or longer where I cut it just turned it.. I used KOQ's front and swinger.. Really nice stuff! Don't do the ebay front brackets.. Did that first and still have the bent ones to show! When I decided to do this alot of people on here helped me along with Tom from KOQs.. I have pictures of the build if they will help you.. The hardest was to find a rear sproket to fit the 400 axle but use the same chain as the CR 85 engine, untill... I called Hetrick and they had everything in stock to make it work!! We drag race this bike here in VA.. Unbeatin so far.. "knock on wood!" That is why the tires are on there. Plus since the pics I have put Elkas all the way around it..

Anyways Anything I can do to help let me know..

David

post some pics i wanna see

[yamaharacer47]

I will keep u all posted and throw some pics on soon.

[st8jacket]

if anyones interested in a 250r frame with a worked cr80 engine,the one on the first page is going to be forsale soon..Moving up to 250four stroke class..frames been gusseted,powdercoated..a few welded after powder but not noticible at all..engine will come with custum pipe and silencer...just add either stock 250r suspention or whatever and youll have a nice mini..this quad was comming in right behind lost creek cycles jb fisher's90 mod and wiley mods cobra..two well know very fast minis around here..

what comes with it as of now..
frame
engine
pipe
carb
electronics..

maybe my brother will see this and chime in if anything else is included..

[yamaharacer47]

Another thing any idea where to start on gear ratio , I'm running 18 " holeshots on rear ???

[st8jacket]

for the honda 80 we were running between a 13-15 tooth front with a 49 rear..with custom sprockets from rebal gear in 428 series chain..18'' hole shots and front teeth varied on track..a 13 was nice very snappy and kept it in the power band all around the track..We dipped down to a 14-15 on slick muddy tracks to rob a bit of hit off the tires..But that should get you in the ball park,your porting is gonna be considered when getting it ''right''..we liked it when it stayed in the PB comming out of a nice tight corner without boggin to much if any,and not over reved when goin down a straight..Urs is a yz but the same theory should apply..But were not proffesional builders by a longshot but have been doing this for a long time..

[barrettbrothers]

For the guys that have put the cr80 in a trx frame did you see frame issues. Is there a fabricator that is willing to install the engine mounts?

[st8jacket]

the engine can be installed withour hacking the frame at all...so when and if the time arises a trx250r engine can simply be dropped in..Or what ever you choose..

[yamaharacer47]

Thanks I went with a 13 tooth front in a 520 chain and running the 300ex rear I can play with the ratio there , thats what the guy at rebelgears suggested . i cant wate to start on this along with my son. Thanks for all the info u all .....

[barrettbrothers]

I have talked to Kenny Vaughn with K-Fab we will start are build in a few weeks. CR80 TRX 90 Frame with Robbs Racing suspension.

[yamaharacer47]

sweet keep us all posted

[yamahaboy47]

pics

[yamahaboy47]

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